You've written your book. Now comes the part that quietly trips up more first-time authors than anything else: formatting it so Amazon KDP actually accepts it and it looks professional in a reader's hands. Get this wrong and you'll either face frustrating upload rejections or, worse, a printed book with cramped margins and text that runs into the spine. Here's how to do it right.
Start with your trim size
Trim size is the physical dimensions of your printed book, and you choose it before you format — because everything else depends on it. The most popular size for novels and non-fiction is 6" x 9", which looks professional and prints economically. Smaller sizes like 5" x 8" suit pocket-style fiction; larger sizes suit workbooks and children's books.
Pick your trim size first, then build your interior to match. Changing it later means reformatting the whole book.
Set your margins and gutter correctly
This is the single most common formatting mistake. Your margins are the white space around the text, and your gutter is the extra inner margin near the spine where the book binds. If your gutter is too small, text disappears into the spine when the book is held open.
KDP requires larger inside margins for longer books because thicker books need more gutter. As a rough guide, a typical book needs at least 0.75" inside margins, scaling up for higher page counts. Always check KDP's current margin requirements for your page count before finalizing.
Choose readable fonts
Resist the urge to get fancy. Professional books use clean, readable serif fonts for body text — think Garamond, Minion, or similar — usually between 10 and 12 point. Your chapter titles can have personality, but your body text should disappear into readability. Two fonts maximum: one for body, one for headings. More than that looks amateur.
Embed your fonts in the final PDF so they print exactly as designed, regardless of what software KDP uses on its end.
Build proper front matter
Front matter is everything before your story starts, and a professional book includes it in the right order: a title page, a copyright page, an optional dedication, and a table of contents for non-fiction (and for fiction with named chapters). Skipping these makes a book feel self-published in the bad sense. Including them — properly ordered — signals quality.
Mind your page breaks and chapter starts
Each chapter should start on a fresh page, ideally a right-hand page for print. Use proper page breaks, never a string of pressed Enter keys to push text down — that breaks the moment you change anything. Consistent chapter openings, running headers, and page numbers are the details that separate a professional layout from a Word document saved as PDF.
Export the right file type
For print, KDP wants a PDF — and ideally a print-ready PDF/X with embedded fonts and the correct color setup. For ebooks (Kindle), the preferred format is a reflowable EPUB, not a fixed PDF, so the text adapts to any screen size and font setting the reader chooses.
These are different files for different purposes. A common mistake is uploading a print PDF as your ebook — it results in a clumsy, un-resizable Kindle book.
The mistakes that get books rejected or returned
A few recurring problems cause most KDP headaches: margins or gutters too small for the page count, images at low resolution (KDP wants 300 DPI for print), a cover sized for the wrong page count (cover spine width depends on your final page count and paper), fonts not embedded, and bleed set up incorrectly for images that run to the page edge. Each of these is fixable — but each one costs you a re-upload cycle and delays your launch.
Should you DIY or hire help?
Honestly? If you're comfortable with software, patient, and publishing a straightforward text-only book, you can learn to format it yourself — plenty of authors do. The tradeoff is time and the learning curve, and the risk of subtle issues you won't notice until you hold the printed proof.
If your book has images, tables, a complex layout, or you simply want it done right the first time so you can focus on writing and marketing, professional formatting pays for itself in saved hours and a polished result. That's exactly what we do — our formatting service delivers print-ready and ebook files built correctly for KDP from the start, so you skip the rejection cycle entirely.
The bottom line
Formatting for KDP isn't magic, but it's detail-heavy, and the details are exactly what readers notice (often subconsciously) when they decide whether a book feels professional. Get your trim size, margins, fonts, front matter, and file types right, and your book will both pass KDP's checks and look like it belongs on a shelf.
Book Design Co formats books for KDP, IngramSpark, and every major platform. See how we can help.